1. Field of the Invention
This invention relates, generally, to the dissolution of a fluids and more particularly to fluid contacting systems.
2. Description of the Prior Art
There are many types of fluid contacting systems. A contact tank, or chamber, is commonly used to transfer a gas bubble to the bulk of the process water in a contacting system. Efficient mixing of the gas and the process water within the contacting system is critical in maximizing the performance of the system. More specifically, when a gas has a low solubility in water, the effective transfer of the gas to the liquid is critical.
Several types of fluid contactors have been developed with the most common including contactors that use diffused bubbles, positive pressure injection, negative pressure, a turbine mixer tank, and a packed tower. Diffused bubble contactors can have either a concurrent or countercurrent configuration. Countercurrent bubble contactors are the most efficient and cost effective of the alternatives and have been employed in the design of most gas dissolution systems. Positive pressure injection is most often employed with a U-tube where an eductor or Venturi tube provides negative pressure means to inject gas into the liquid flow.
Continuing efforts are being made to improve gas-liquid contacting tanks. By way of example, U.S. Pat. No. 5,968,352 to Ditzler that describes a contact chamber with concentric inner and outer tanks. Water is injected with gas prior to the water entering the concentric tanks. The gas-enriched water enters the tank configuration via a conduit and is discharged near the bottom of the inner tank so that it flows upwards to the top of the inner tank. As the water nears the top of the inner tank, the water overflows to the concentric outer tank where the water then flows downwards to the bottom of the outer tank and out.
U.S. Pat. No. 6,207,064 to Gargas describes a cylindrical contact tank that discharges gas-containing water near the upper end of the tank in a tangential orientation. The tangential discharge causes a turbulent swirling motion of the water within the tank to promote further gas contact with the water.
Similarly, U.S. Pat. No. 6,054,046 to Nelson describes a contact tank having a vortex chamber that creates a downward spiral flow of the gas-containing liquid stream.
The prior art does not utilize a concurrent flow of gas and liquid for facilitating the dissolution of gas in a liquid without the use of positive pressure or diffusers.
A fluid contacting system that improves the transfer of fluid contact which is simple in design and economical to maintain and operate is needed.
However, in view of the prior art considered as a whole at the time the present invention was made, it was not obvious to those of ordinary skill in the pertinent art how the identified needs could be fulfilled.
The long-standing but heretofore unfulfilled need for a contacting apparatus that increases the fluid contact that is simple in design and economical to maintain and operate is now provided in the form of a new, useful and non-obvious device.
The contacting apparatus includes a contactor and a liquid source that is in fluid communication with a flow splitter. The flow splitter is in further interposing fluid communication with a flow adjustment means and a gas injection means. The flow splitter splits the liquid influent into upper and lower streams. The upper stream is directed to the flow adjustment means and the lower stream is directed to the gas injection means. The flow adjustment means is in fluid communication with the splitter and an upper fluid flow directing means. The flow adjustment means is adjusted so that the upper stream flows at a desired flow rate. The upper stream is discharged tangentially at the desired flow rate via the upper fluid flow directing means. The upper fluid flow directing means is disposed proximate to the top of the contactor and at a preselected downward angle so that the upper stream discharge direction and velocity produces a downward vortex flow within the contactor. The gas injection means is in fluid communication with a gas source and is interposed between the flow splitter and a lower fluid flow directing means. The gas from the gas source is injected concurrently with the lower stream via the gas injection means to produce a gas-enriched lower stream. The lower fluid flow directing means is disposed proximate to the bottom of the contactor and at a preselected upward angle so that the gas-enriched lower stream discharge direction and velocity produces an upward vortex flow that is counter to the downward vortex flow within the contactor. A mixing zone is created by the upward and downward vortices because the gas-enriched lower stream flows in an upwardly direction and the upper stream flows downwardly to an outlet thereby producing a mixing countercurrent flow within the contactor. The outlet is disposed proximate to the bottom of the contactor. A gas collector disposed proximate to the top of the contactor collects gas not transferred to the liquid and recirculates the collected gas to an outlet conduit.
In an alternative embodiment of the invention, a fluid having a density lighter that the liquid may be substituted for the gas. Thus, a first liquid and a second liquid may be dissolved using the present invention provided they exhibit distinct densities. Accordingly, the second liquid rises in counter-vortex relation to the denser first liquid flowing downward.
It should be noted that virtually any gas including, but not limited to, ozone, ammonia, oxygen, carbon dioxide, nitrogen and the like may be dissolved using this novel invention. Additionally, the present invention may be used to dissolve together two fluids, each in a liquid state.
Potential applications for the present invention include, but are not limited to, laundry cleaning, swimming pool applications, produce washing, fish farm maintenance, hog farm effluent processing, toxic waste decontamination, industrial chemical processing, and the like.
An important object of the present invention is to provide an improved contacting apparatus that increases the efficiency of the transfer of gas to a liquid and thereby reduces operating costs.
Another object of the present invention is to provide a contacting apparatus that reduces maintenance requirements.
These and other important objects, advantages, and features of the invention will become clear as this description proceeds.
It is to be understood that both the foregoing general description and the following detailed description are explanatory and are not restrictive of the invention as claimed. The accompanying drawings, which are incorporated in and constitute part of the specification, illustrate embodiments of the present invention and together with the general description, serve to explain principles of the present invention.
The invention accordingly comprises the features of construction, combination of elements, and arrangement of parts that will be exemplified in the description set forth hereinafter and the scope of the invention will be indicated in the claims.